Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$233.50	8.546%	$253.4549	$253.45	$253.45	$253.50
Purchase #2	$93.81	12.109%	$105.1695	$105.17	$105.15	$105.20
Purchase #3	$216.28	6.866%	$231.1298	$231.13	$231.15	$231.10
Purchase #4	$127.64	5.448%	$134.5938	$134.59	$134.60	$134.60
Purchase #5	$144.97	9.307%	$158.4624	$158.46	$158.45	$158.50
Purchase #6	$14.66	6.865%	$15.6664	$15.67	$15.65	$15.70
Purchase #7	$237.25	6.408%	$252.453	$252.45	$252.45	$252.50
7 purchase totals =	$1,068.11		$1,150.9298	$1,150.92	$1,150.90	$1,151.10